1. Field of the Invention
The present invention relates to a vacuum circuit breaker, and more particularly, to an interlock apparatus for a vacuum circuit breaker capable of preventing the occurrence of an accident by preventing a breaker body from moving to a connection position (in other words push-in position) for connection to terminals of an enclosure from a disconnection position (in other words draw-out position) for separation from the terminals of the enclosure, or by preventing the breaker body from moving to the disconnection position from the connection position, in a state that a closing spring for a closing operation is charged with elastic energy.
2. Background of the Invention
Generally, a circuit breaker for protecting an electric power circuit and an electric load devices by automatically breaking the circuit upon detection of an abnormal current on the circuit or for switching the electric power circuit, may be categorized into a low voltage circuit breaker for a low voltage less than several hundreds of volts, and a high voltage circuit breaker for a high voltage more than several hundreds of volts according to the size of a rated voltage.
A vacuum circuit breaker is the high voltage circuit breaker and may be categorized into a fixed type vacuum circuit breaker, and a movable type vacuum circuit breaker movable in an enclosure such as an electric power distribution board so as to be connected to or disconnected from the enclosure.
The movable type vacuum circuit breaker is more used worldwide than the fixed type vacuum circuit breaker, since a breaker body can be separated from terminals of an enclosure for test, repair and replacement (movable to a disconnection position) and can be connected to the terminals of the enclosure after test, repair and replacement (movable to a connection position).
For the connection or disconnection, the breaker body is provided with wheels together with a driving device at a lower part thereof.
The draw-out type vacuum circuit breaker has a closing position (ON′ position) for supplying an electric power in a state an electric circuit is closed, and a breaking position (‘OFF’ position or ‘TRIP’ position) for breaking the electric power supply by making an electric circuit be opened state. Here, the vacuum circuit breaker may be movable to the closing position or the breaking position, by extension of a closing spring or a trip spring for discharging charged energy, respectively. In the occurrence of an abnormal current on the electric power circuit, the circuit has to be instantaneously interrupted. Accordingly, the closing spring and the trip spring have very high elastic energy, respectively.
In the draw-out type vacuum circuit breaker, the breaker body may be separated from terminals of an enclosure for test, repair and replacement, or may be connected to the terminals of the enclosure after test, repair and replacement.
If the closing spring of the vacuum circuit breaker is in a charged state while the breaker body is connected to or disconnected from the enclosure, the elastic energy charged in the closing spring may be discharged. This may result in injury to a user.